Prior patents relevant to the instant invention include: (1) U.S. Pat. No. 4,640,461 (Williams) directed to a self educting foam fog nozzle; (2) U.S. Pat. No. 5,779,159 (Williams) directed to a peripheral channeling additive fluid nozzle; and (3) U.S. Pat. Nos. 5,275,243; 5,167,285 and 5,312,041 (Williams) directed to a chemical and fluid or duel fluid ejecting nozzle. Also relevant is the prior art of automatic nozzles, including (4) U.S. Pat. Nos. 5,312,048; 3,684,192 and 3,863,844 to McMilian/Task Force Tips and U.S. Pat. Nos. Re 29,717 and 3,893,624 to Thompson/Elkhart Brass. Also of note are U.S. Pat. No. 5,678,766 to Peck and PCT Publication WO 97/38757 to Baker.
Maintaining a constant discharge pressure from a nozzle tends to yield a constant range and “authority” for the discharge while allowing the nozzle flow rate to absorb variations in head pressure. In certain applications, such as vapor suppression, a fire fighting nozzle is useful if it self regulates to discharge at an approximately constant or targeted pressure. The discharge pressure tends to govern what is referred to as the “authority” of the discharge stream and to a certain extent the stream's range, and it can affect the delivery of an appropriate vapor-suppressing fog.
One application in which a self-regulating nozzle may be useful, thus, is a protection system that includes nozzles permanently stationed around locales that could be subject to the leakage of toxic chemicals. Upon leakage such a permanently stationed configuration of nozzles, probably under remote control, would be optimally activated to provide a predesigned curtain of water/fog to contain and suppress any toxic vapors. In such circumstances it may be optimal for the nozzles to discharge their fluid with a more or less constant range and authority as opposed to having their discharge structured and regulated for a relatively constant flow rate, as is more common among fire fighting nozzles. Water/fog created with a more or less constant range and authority while operating under the conditions of varying head pressure from a fixed nozzle will tend to more reliably form a curtain in a preselected region, again which may be useful for containing escaping vapors from a fixed locale.
Typically nozzles are structured to deliver pre-set gallon per minute flow rate assuming a nominal head pressure such as 100 psi at the nozzle. As the head pressure actually available to the nozzle in an emergency varies, flow rate remains more consistent with such design than does discharge pressure. Structuring a nozzle to alternately target and regulate its discharge pressure will let flow rate vary more with variations in delivered pressure, but may be an optimal design for certain circumstances.
The present invention, in one important aspect, discloses an improved pressure regulating nozzle designed within its operating limits to effectively discharge a fire extinguishing fluid at a pre-selected or targeted discharge pressure. According to current practice this targeted discharge pressure would likely be approximately 100 psi. It is to be understood, however, that the preselected targeted pressure could be easily varied, and a target pressure might more optimally be selected to be 120 psi. The instant inventive design improves the efficiency of achieving such a target pressure as well as offers a design that more easily combines with self-educting features for foam concentrates and with the capacity to throw fluid chemicals, such as dry powder, from the nozzle.
In another important aspect the present invention teaches enhanced eductive techniques, for peripheral and central channeling, which enhanced eduction can be particularly helpful in automatic nozzles or when also throwing chemical such as dry powder.
A typical automatic nozzle designed in accordance with the present invention would be designed to operate over a range of flow rates, such as from 500 gallons per minute to 2000 gallons per minute, at a targeted discharge pressure, such as 100 psi. To target a discharge pressure, or to self regulate pressure, the nozzle design incorporates a self-adjusting baffle proximate the nozzle discharge. In general, when fluid pressure at the baffle, sensed more or less directly or indirectly, is deemed to lie below target, the baffle is structured in combination with the nozzle to “squeeze down” on the effective size of the discharge port for the nozzle. When pressure build-up at the baffle, as sensed directly or indirectly, is deemed to reach or exceed a targeted pressure, the baffle is structured to cease squeezing down and, if necessary, to shift to enlarge the effective size of the annular discharge port. Such enlargement would continue, in general, until the discharge pressure reduces to the preset target or a limit is reached. Such adjustments in the size of the discharge port cause the flow rate to vary, but the fluid that is discharged tends to be discharged with a more constant “authority” and range, an authority and range associated with the targeted pressure. The instant design is structured to improve the efficiency and reliability of settling upon or around a target pressure.
The instant invention achieves a pressure regulating system by providing a design with an adjustable baffle having what is referred to herein as forward and opposing or reverse fluid pressure surfaces. Pressure from fluid applied to opposing sides of the baffle causes the baffle to respond, at least to an extent, as a double acting piston, although perhaps in a complex manner. The so called forward and reverse directions are referenced to the nozzle axial direction with forward being in the direction of fluid discharge. The forward and reverse pressure surface areas provided by the baffle preferably are not equal. In preferred embodiments the effective pressure surface area of the reverse side exceeds the effective pressure surface area of the forward side. Thus, were the pressure on both surfaces equal, the baffle would automatically gravitate to its most closed position, minimizing or closing the discharge port.
The effective forward pressure surface area will likely, in fact, vary with pressure and with flow rate Limited experience indicates that the forward fluid pressure surface area also varies with bafflehead design and nozzle size. Further, in preferred embodiments, although pressure from the primary fire fighting fluid, directly or indirectly, is applied to both forward and opposing fluid pressure surfaces, the value of the reverse pressure is usually less than, although a function of, the pressure on the forward surface.
A relief valve is preferably provided, such that at or slightly past a targeted pressure the valve can begin to relieve the effective pressure on (at least) one side of the baffle. At least one relief value promises to enhance responsiveness. In preferred embodiments the one side of the baffle upon which pressure is relieved would be the reverse side, the side opposing the forward pressure of the primary fluid on the bafflehead. Specifically, in such an embodiment, when the pressure of the primary fire extinguishing fluid proximate the nozzle discharge causes the pressure sensed by whatever means by the relief valve to exceed a pre-selected value, reverse pressure is relieved on the interior baffle chamber surfaces and the baffle tends to forwardly adjust in response to forward fluid pressure. Alternately, the baffle might simply stabilize at a balanced pressure position in preferred embodiments, with or without the (or a) relief valve slightly bleeding. That is, a nozzle could be designed to achieve a balanced pressure baffle position with or without a relief valve and with or without any bleeding of a relief valve. Use of at least one relief valve, and a bleeding relief valve, are practical expedients.
To continue the prior example, adjustments forward of a bafflehead may continue until the primary forward fluid pressure at the bafflehead, as sensed directly or indirectly, decreases to or diminishes below a preset relief valve value. Thereupon a closing of the relief valve would be triggered. The bafflehead might stabilize, or if stabilization were not achieved, could adjust backwardly with the relief valve either bleeding or closed, depending on the design, thereby decreasing the effective size of the nozzle discharge port.
To summarize operations, as the bafflehead adjusts forward and backward, as described above, the discharge pressure declines and increases, respectively. If a discharge pressure declines to, or below, a pre-selected amount, as sensed directly or indirectly, in preferred embodiments as described above, a relief valve would be set so that it tends to close. Closing the relief valve would increase reverse pressure on the baffle. Alternately if a sensed delivered pressure is deemed to increase above a preselected amount, the (or a) relief valve would preferably be set so that it tends to open. With the assistance of the opening and closing of a relief valve, a bafflehead can be encouraged to quickly and efficiently gravitate toward a balanced location wherein the effective pressure on the bafflehead in the forward direction offsets the effective pressure on the bafflehead in the reverse direction, taking into account the degree of openness, and any bleeding, of a relief valve or valves, as well as other factors of the design and the supplied pressure. Of course, other biasing factors on the bafflehead, such as springs, etc. could be present and would have to be taken into account.
Again, assuming that the reverse pressure surface area afforded by the bafflehead chamber is larger than the effective forward pressure surface area afforded by the bafflehead, and that the reverse side of the baffle is supplied with a measure of fluid pressure from the primary fire fighting fluid as delivered to the nozzle then a bafflehead and nozzle could be designed (ignoring the effects of any relief valve activation) so that as the pressure of the fire extinguishing fluid through the nozzle decreases, the bafflehead adjusts in the reverse direction until it either closes or hits a stop or balances (or triggers a relief valve). Squeezing down on the size of the discharge port raises discharge pressure. Again, as stated above, a design could incorporate, without any relief valves, a balanced pressure position where, at target pressure, the effective pressure on the baffle forward pressure surface offsets the effective pressure on the opposing reverse baffle surface. The design would take into account the fact that the pressures and the areas would be different and would typically vary. In general, however, the bafflehead forward surfaces and reverse surfaces together with the nozzle discharge structure, baffle structure and any relief valves and any other supportive biasing means, should be designed and structured in combination such that a targeted discharge pressure is effectively and efficiently achieved without undue hunting. As mentioned above, a relief valve or valves likely improve the efficiency of the design and, at the balance point, might be optimally structured to be slightly open, or bleeding.
Further to summarize operations, pressure forward on the bafflehead is the product of the delivered fluid pressure at the effective bafflehead deflecting surface times the effective baffle forward surface area. The opposing pressure on the bafflehead is the fluid pressure developed against the bafflehead opposing surface (preferably the primary fluid operating within a baffle chamber) times the opposing bafflehead surface area. The opposing surface area is preferably larger than the effective forward surface area, and reverse fluid pressure, such as developed within a baffle chamber, is likely less than, although a function of, the delivered fluid pressure at the bafflehead. As stated above, while it is possible to design a self adjusting bafflehead in combination with a nozzle structure such that a bafflehead balances at a targeted pressure without the assistance of any relief valves, a relief valve likely facilitates the speed, sensitivity and efficiency of the design for most nozzle sizes. So, using one or more relief valves, a valve trigger pressure would be selected such that, when fluid pressure on forward baffle surfaces appears to a sensing device to begin to significantly exceed the target pressure, the relief valve opens or at least begins to open. At such point the valve relieves or begins to relieve fluid pressure on one baffle surface, such as the reverse surface, allowing the baffle to stabilize or to begin to readjust. The readjustment affects fluid discharge pressure at the discharge port. One preferred design includes structuring of bafflehead surface area and a relief valve in combination such that with the relief valve closed, the bafflehead essentially closes the nozzle; further, the bafflehead balances at a targeted delivery pressure with the relief valve partially open or bleeding. With the relief valve completely open, the bafflehead would move to its fully open position.
The present invention has at least three objectives. One objective is to provide an automatic self adjusting nozzle that can accurately, speedily and reliably control nozzle discharge pressure to within a small range. A second objective is to provide a self adjusting nozzle design that adjusts smoothly and accurately in both directions, that is both from a too high pressure situation and from a too low pressure situation toward a target pressure. Structure to accomplish these two objectives has been discussed above. Third and further objectives are to provide an enhanced self educting nozzle design, valuable in its own right and also so that a self-adjusting nozzle can be efficiently combined and incorporated into a self-educting foam/fog nozzle. In addition the enhanced eductive design is useful to incorporate with a nozzle incorporating a capacity for throwing fluid chemicals, such as dry powder. Thus, the invention also relates to improved educting features applicable to various nozzles. The invention also includes methods and apparatus for metering a chemical, such as a foam concentrate, into a variably flowing fire fighting fluid conduit at the nozzle, or upstream from a nozzle device or devices.